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-rw-r--r--contrib/atomicrename/main.go101
1 files changed, 101 insertions, 0 deletions
diff --git a/contrib/atomicrename/main.go b/contrib/atomicrename/main.go
new file mode 100644
index 0000000..67088b0
--- /dev/null
+++ b/contrib/atomicrename/main.go
@@ -0,0 +1,101 @@
+package main
+
+import (
+ "bytes"
+ "flag"
+ "fmt"
+ "io/ioutil"
+ "os"
+ "strings"
+ "sync/atomic"
+ "syscall"
+)
+
+const fileCount = 100
+
+type stats struct {
+ renameOk int
+ renameError int
+ readOk int
+ readError int
+ readContentMismatch int
+}
+
+func usage() {
+ fmt.Printf(`atomicrename creates %d "src" files in the current directory, renames
+them in random order over a single "dst" file while reading the "dst"
+file concurrently in a loop.
+
+Progress and errors are reported as they occour in addition to a summary
+printed at the end. cifs and fuse filesystems are known to fail, local
+filesystems and nfs seem ok.
+
+See https://github.com/hanwen/go-fuse/issues/398 for background info.
+`, fileCount)
+ os.Exit(1)
+}
+
+func main() {
+ flag.Usage = usage
+ flag.Parse()
+
+ hello := []byte("hello world")
+ srcFiles := make(map[string]struct{})
+
+ // prepare source files
+ fmt.Print("creating files")
+ for i := 0; i < fileCount; i++ {
+ srcName := fmt.Sprintf("src.atomicrename.%d", i)
+ srcFiles[srcName] = struct{}{}
+ buf := bytes.Repeat([]byte("_"), i)
+ buf = append(buf, hello...)
+ if err := ioutil.WriteFile(srcName, buf, 0600); err != nil {
+ panic(err)
+ }
+ fmt.Print(".")
+ }
+ fmt.Print("\n")
+
+ // prepare destination file
+ const dstName = "dst.atomicrename"
+ if err := ioutil.WriteFile(dstName, hello, 0600); err != nil {
+ panic(err)
+ }
+
+ var running int32 = 1
+
+ stats := stats{}
+
+ // read thread
+ go func() {
+ for atomic.LoadInt32(&running) == 1 {
+ have, err := ioutil.ReadFile(dstName)
+ if err != nil {
+ fmt.Println(err)
+ stats.readError++
+ continue
+ }
+ if !strings.HasSuffix(string(have), string(hello)) {
+ fmt.Printf("content mismatch: have %q\n", have)
+ stats.readContentMismatch++
+ continue
+ }
+ fmt.Printf("content ok len=%d\n", len(have))
+ stats.readOk++
+ }
+ }()
+
+ // rename thread = main thread
+ for srcName := range srcFiles {
+ if err := os.Rename(srcName, dstName); err != nil {
+ fmt.Println(err)
+ stats.renameError++
+ }
+ stats.renameOk++
+ }
+ // Signal the Read goroutine to stop when loop is done
+ atomic.StoreInt32(&running, 0)
+
+ syscall.Unlink(dstName)
+ fmt.Printf("stats: %#v\n", stats)
+}